The Facts

An ectopic pregnancy occurs when a fertilized egg implants itself outside of the uterus. Ectopic pregnancies usually occur in a fallopian tube (called a tubal pregnancy). Occasionally, the egg may lodge itself in the ovary, and more rarely, in the cervical canal or the abdominal or pelvic cavities. The fertilized egg doesn't usually grow into a recognizable embryo and can't be transplanted into the uterus.

In a normal pregnancy, the egg is fertilized in the fallopian tube. Little hairs in the fallopian tube move the egg down to the uterus, where it implants itself. If there's scar tissue in the fallopian tube, or it's blocked for some other reason, the fetus will begin to grow outside of the uterus. A woman who has an ectopic pregnancy must have the pregnancy removed because the fetus can't develop properly outside of the uterus and it is dangerous to the woman's health.

Although they're becoming more common in recent years, ectopic pregnancies are generally rare. About 2% of pregnant women will have an ectopic pregnancy.

Causes

If you've had an infection in the pelvic region (e.g., pelvic inflammatory disease) or pelvic surgery, or were born with a medical condition that narrowed your fallopian tubes, you have a greater chance of having an ectopic pregnancy. A previous ectopic pregnancy can also increase your risk of a second ectopic pregnancy. An unsuccessful tubal ligation, a sterilization procedure in which the fallopian tubes are cut or blocked, can contribute to the risk of an ectopic pregnancy.

Rarely, ectopic pregnancies have also been linked to the use of progesterone-only birth control pills, and the morning-after pill. Women who use intrauterine devices (IUD, a type of birth control), especially those containing progesterone, have a higher risk of having an ectopic pregnancy if they do become pregnant despite using the IUD. Women who were exposed to a medication called diethylstilbestrol* (a synthetic estrogen) in their mother's womb are also at greater risk of ectopic pregnancy.

The use of certain assisted reproductive techniques may also increase the risk of ectopic pregnancy, as can having multiple sexual partners and cigarette smoking.

Symptoms and Complications

Irregular vaginal bleeding or a missed period can be a sign of an ectopic pregnancy, although some women with an ectopic pregnancy continue to menstruate. Most ectopic pregnancies are discovered before the woman even knows she's pregnant.

The growing fetus can damage or rupture the tissue around the reproductive organs, causing internal bleeding and severe pain. If the pregnancy tissue grows too large, it may damage the walls of the fallopian tube. The bleeding that results can be painful and create a feeling of fullness in the abdomen. Severe bleeding can cause a woman's blood pressure to drop to the point where she shows symptoms of shock, including paleness, sweating, weakness, and faintness.

The ectopic pregnancy usually ruptures the wall of the fallopian tube in Weeks 6 to 8 since the last period. An ectopic pregnancy that implants partly in the fallopian tube and partly in the uterus usually ruptures later, between Weeks 12 and 16 of pregnancy. A woman whose fallopian tube has ruptured will feel severe pain that comes on suddenly, and will often faint due to massive internal bleeding in the abdomen. A rupture that occurs later in the pregnancy is very dangerous and can lead to death.

Making the Diagnosis

The doctor will do a pelvic examination, blood tests, and ultrasound to check for an ectopic pregnancy. If your blood or urine tests show you're pregnant, but your uterus isn't getting bigger, you may have an ectopic pregnancy. Blood tests that show low levels of human chorionic gonadotropin (hCG) or a slower than usual rise in hCG can point to an ectopic pregnancy.

An ultrasound scan will then be done to see if the uterus is empty. The scan can also show blood in the abdominal or pelvic cavities. A fibre-optic tube attached to a camera called a laparascope can be inserted through the abdomen to allow the doctor to look inside the uterus. Rarely, a procedure called culdocentesis may also be done to look for unusual fluid in the area behind the uterus.

Treatment and Prevention

If an ectopic pregnancy occurs, the doctor must remove the fetus and placenta from the fallopian tube or other area where it has become implanted. This may be done by using the medication methotrexate or laparoscopic surgery.

The medication methotrexate is used to treat early tubal pregnancies in cases where the ectopic pregnancy is believed to be at a low risk of rupturing. It causes the pregnancy to break down and be reabsorbed.

Laparoscopic surgery is also used as a treatment option for ectopic pregnancy if the woman's health is unstable, if there are reasons not to use methotrexate, or in cases of non-tubal ectopic pregnancies, later-term tubal pregnancies, or tubal pregnancies where there is a significant risk of rupture. In this procedure, the doctor inserts a thin tube into the abdominal cavity. The tube has a camera and surgical instruments attached to it.

If the pregnancy is in the fallopian tube, the tube is cut and left to heal naturally, so that scar tissue from the wound doesn't block the fallopian tube. A blocked fallopian tube can make it difficult for a woman to have another baby. In many cases, the fallopian tube must be removed because it's been severely damaged as a result of the ectopic pregnancy. A woman with only one fallopian tube can still become pregnant. If there has been severe bleeding, a blood transfusion may be needed.

While it is not possible to prevent all forms of ectopic pregnancy, there are a few things you can do to reduce your risk of a tubal ectopic pregnancy (an ectopic pregnancy occurring in the fallopian tube), which is the most common type of ectopic pregnancy. Pelvic inflammatory disease (PID) and sexually transmitted infections (STIs) are frequent causes of tubal ectopic pregnancies. Both are preventable. Talk to your doctor about ways to reduce your risk of PID and STIs, such as using condoms and quickly seeking treatment for any infections of the genitals, abdomen, or bladder areas.

*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For information on a given medication, check our Drug Information database. For more information on brand names, speak with your doctor or pharmacist.